Schedule Jan 17, 2009
Simple 2-Component Models of Stellar Systems
Rosemary Apple (Univ. of Edinburgh)

The results of N-body simulations (e.g. Giersz and Heggie 1996) show that, although the masses segregate as expected during core collapse, after core collapse there is self-similar evolution with very little further evidence of mass segregation even though the system has not reached equipartition. Binary stars halt core collapse through binary heating and power the post-collapse expansion. It is possible that binary heating could also play a role in maintaining the lack of equipartition. To investigate this problem and to gain insight into two-component systems (i.e. a stellar system consisting of two populations each with a different stellar mass), we create a simple two-component model which only considers gravitational interactions and binary heating. We also compare our model with our own two-component N-body simulations (performed using a GPU for simulations with larger values of N). We found that our simple model exhibits behavior similar to our N-body simulations; the post-collapse evolution is self-similar and there is no further mass segregation even though the system is not in equipartition. We conclude that the processes considered in our simple model are enough to prevent mass segregation to develop further in= stellar systems which have undergone core collapse.

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